My columnar SCSS file

column.scss

$columnsmax: 16;
$columnwidth: 40px;
$gutterwidth: 20px;


$widthmax: ($columnsmax * $columnwidth) + (($columnsmax - 1) * $gutterwidth);

@function grid($cols: 1) {
  $width: ($cols * $columnwidth) + (($cols - 1) * $gutterwidth);
  @return percentage($width/$widthmax);
}

@function gutter() {
  @return percentage($gutterwidth/$widthmax);
}

@function gridgutter($cols: 1) {
  @return gutter() + grid($cols);
}

@function innergrid($outercols:1, $innercols:1) {
  $columnsinnerpx: ($innercols * $columnwidth) + (($innercols - 1) * $gutterwidth);
  $columnsouterpx: ($outercols * $columnwidth) + (($outercols - 1) * $gutterwidth);
  @return percentage($columnsinnerpx/$columnsouterpx);
}

@function innergutter($outercols:1) {
  $columnsouterpx: ($outercols * $columnwidth) + (($outercols - 1) * $gutterwidth);
  @return percentage($gutterwidth/$columnsouterpx);
}